1. Field of the Invention
The present invention relates to an ink jet printing head, and particularly, to a printing head in an ink jet printing apparatus for performing a printing operation by ejecting a print liquid such as ink onto a print medium.
2. Description of the Related Art
An ink jet printing apparatus is a printing apparatus of a so-called non-impact printing system and generates almost no noise at printing. The ink jet printing apparatus can perform printing at a high speed and onto various types of print mediums. Therefore, the ink jet printing apparatus has been widely adopted as an apparatus performing printing, such as a printer, a word processor, a facsimile machine or a copier.
As a representative ink ejecting system in the ink jet printing apparatus, there is a system using an electrothermal conversion element as a printing element. In the ink jet printing apparatus using this electrothermal conversion element, the electrothermal conversion element is provided in a print liquid chamber and an electrical pulse as a printing signal is applied to the electrothermal conversion element, thereby providing thermal energy to ink. Air bubble pressures at foaming (at boiling) of the ink generated due to a phase change of the ink at this point are used for ejecting of ink liquid droplets.
When a printing head having a large printing width is used, it is possible to perform printing at a high speed. For example, there is known a printing head in which printing element substrates each having a printing width of one inch+α are arranged in a staggered shape in such a manner as to form an overlap region (L) with each other, providing a printing width of four inches as a whole (For example, Japanese Patent Laid-Open No. 2007-160834).
FIG. 10 is a perspective view showing the conventional printing head. A plurality of printing element substrates H1100 are supported and fixed on a large-scaled support member H1200. The printing element substrates H1100 are arranged in a staggered shape in such a manner as to form an overlap region (L) with each other.
In recent years, a higher speed of printing has been demanded, and there is known also a printing head having a printing width of four inches to 12 inches.
In the printing head in which the plurality of the printing element plates are arranged in a staggered shape, particularly in a case of performing the printing at high resolution and at a high grade as in the case of a photograph image, the plurality of the printing element substrates are required to be arranged with high precision by an interval of approximately several μm from each other. In the conventional support member for supporting the printing element substrates, it is made of a sintered element of alumina. This alumina-sintered element generally causes a dimension error of approximately ±1%. Therefore, in a case where in an elongated support member having a length equal to or more than four inches, for example, 12 inches, ink supply openings are sintered and formed, the position dimension precision of the ink supply opening has the technical problem consequently.
FIG. 11 is a diagram explaining a state where the ink supply opening H1101 in the printing element substrate H1100 shown in FIG. 10 and an ink introduction opening H1201 in the support member H1200 are shifted in position from each other. This figure shows a schematic cross section taken along line XI-XI in FIG. 10. The printing element substrates are arranged with position precision of several μm from each other on the support member H1200, but in a case of a printing head having a printing width of four inches, a distance M made by the remotest positions of the ink introduction openings H1201 of the support member H1200 produces a variation of approximately ±1 mm. In consequence, the ink supply opening H1101 in the printing element substrate H1100 and the ink introduction opening H1201 in the support member H1200 are shifted in position from each other. Therefore, the bonding area between the printing element substrate H1100 and the support member H1200 can not be sufficiently secured and the ink may be leaked therebetween. Further, the bonding area may not be secured at all.
For forming the ink introduction opening H1201 at an accurate position for the purpose of overcoming the above problem, there is also a method of forming the ink introduction opening by machining after alumina sintering. In the method of forming the ink introduction opening by machining after the alumina sintering, however, it leads to a large increase in cost of the printing head.